1. Field of the Invention
The present invention relates to novel imidazole derivative. More particularly, the present invention relates to 4-(1-imidazolylmethyl)cinnamic acid hydrochloride monohydrate of the formula (I): ##STR2## and to pharmaceutical compositions containing such compound.
2. Description of the Prior Art
It has been reported that 4-(1-imidazolylmethyl)cinnamic acid and its pharmaceutically acceptable salt possess a strong and specific inhibitory action for biosynthesis of thromboxane A.sub.2 and are useful for the treatment of diseases caused by thromboxane A.sub.2 such as inflammation, hypertension, thrombus, cerebral apoplexy, and asthma [U.S. Pat. No. 4,226,878]. However the former compound, i.e. free compound, is amphosteric and is hard to be isolated and purified. The latter compound, i.e. salt compound, has highly hygroscopic property and the water contained in said compound varies depending upon moisture in atmosphere in which said compound is allowed to stand. Accordingly, a net weight of said compound tends to vary due to its hygroscopic property by absorbing moisture from atmosphere and taking into consideration that a pharmaceutical composition has always to contain an active agent at a prescribed ratio so as to achieve the expected effects and safety, said compound is not necessarily desirable for preparing pharmaceutical compositions.
From an extensive research and experimentation, we found that such problem was absolutely solved by using the compound of the formula (I) above. That is, the compound of the formula (I) is non-hygroscopic and has a constant net weight without being affected by moisture contained in atmosphere.